Human Impact on Biomes

Human Impact on Biomes

1. Deforestation

   • Causes
     • Intensive agriculture, logging, demand for wood as a fuel, mining & government-organised forest colonisation schemes for farming land.
   • Reasons
     • Economic & social problems: over pop, poverty (political difficulties), take advantage of timber & mineral wealth
     • Beef farmers require more land
   • Government encouraged poor people to move from cities to forests & clear land
     • Some land was given away for free
   • Timber companies were given rights to remove forest & sell timber abroad
     • Government receives a portion of the timber companies profit (pay national debt)
   • Building roads across forests
     • Roads are built to allow access to logging companies etc
     • Longest road: Trans-Amazon Highway (530km east-west Brazil)
   • Building Cities through forests
     • Brasilia built during 50's & 60's
     • Built to encourage people to settle in the forest
   • In Jan 2000, Avanca Brazil was announced by the Brazilian gov
     • Cover the Amazon with 10000km of highways, HEP dams, power lines, mines, logging concessions & other industrial developments
     • €30 billion plan

2. Destruction of Natural Habitats

   • Rainforests are disappearing at about 40 hectares/min day & night
     • Effect of people & wildlife
     • Disrupts natural ecological balance
   • No. of natives in the Amazon Rainforest has decreased dramatically
     • Deforestation
     • Forced to leave (some even murdered)
   • Unidentified species are destroyed before we can discover them opportunity to study them is lost
     • 1400 varieties of tropical plants are thought to contain potential cures for cancer

3. Industrial Activity

   • Vehicles used to clear forest
     • Produce sulphur dioxide (SO2) & nitrogen oxides (NOx)
   • These gases contribute to acid rain when they combine with water vapour to form sulphuric & nitric acid
   • When acid rain falls it kills & damages trees, aquatic life, crops & buildings.
   • Causes nutrient leaching, accumulation of toxic metals & the release of toxic Al into H2O & soil.
   • Nutrient Leaching
     • Acid rain displaces Ca, Mg & K from soil particles, depriving trees from minerals
     • Waxy surface on leaves is broken, nutrients lost
     • Root growth slows down

4. Introduction of Exotic Species

   • Plants grown on plantations (intensive agriculture)
     • Soya Beans
   • These GMOs have the potential to escape & invade natural communities